package com.lagou.edu.interceptor;


import com.alibaba.fastjson.JSONObject;
import com.lagou.edu.callback.Callback;
import com.lagou.edu.callback.JsonData;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.io.PrintWriter;

/**
 * 自定义springmvc拦截器
 */
public class LoginInterceptor implements HandlerInterceptor {


    /**
     * 会在handler方法业务逻辑执行之前执行
     * 往往在这里完成权限校验工作
     * @param request
     * @param response
     * @param object
     * @return  返回值boolean代表是否放行，true代表放行，false代表中止
     * @throws Exception
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object object) throws Exception {
       HttpSession session=request.getSession();
        Object user = session.getAttribute("user");
        if(user==null){
            response.sendRedirect("/login/login?msg=请先登录");
            responseMsg(response, "invalid", "请登录！");
            return false;
        }
        if (!(object instanceof HandlerMethod)) {
            return true;
        }

        return true;
    }


    /**
     * 会在handler方法业务逻辑执行之后尚未跳转页面时执行
     * @param request
     * @param response
     * @param handler
     * @param modelAndView  封装了视图和数据，此时尚未跳转页面呢，你可以在这里针对返回的数据和视图信息进行修改
     * @throws Exception
     */
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

    }

    /**
     * 页面已经跳转渲染完毕之后执行
     * @param request
     * @param response
     * @param handler
     * @param ex  可以在这里捕获异常
     * @throws Exception
     */
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

    }
    private void responseMsg(HttpServletResponse response, String status, String msg) throws IOException {
        JsonData jsonData = Callback.fail(status, msg, "");
        response.setCharacterEncoding("utf-8");
        response.setContentType("application/json; CHARSET=utf-8");
        String json = JSONObject.toJSONString(jsonData);
        PrintWriter out = response.getWriter();
        out.print(json);
        out.flush();
        out.close();
    }
}
